1. Field of the Invention
This invention relates to a process for the production of 1,1-dimethyl hydrazine.
2. Description of the Prior Art
Unsymmetrical dimethyl hydrazine (UDMH) is a versatile chemical intermediate having recognized usefulness in the preparation of surfactants, plant growth regulators, insecticides, dyes, monomers, etc. Currently, the largest volume use thereof is as such in the field of liquid propellants for rockets.
There presently exists two commercially adaptable methods for producing UDMH. The more desirable of these methods from the standpoint of overall efficiency involves the hydrogenation of nitrosodimethylamine in turn obtained by nitrosating dimethylamine. This method suffers because nitrosodimethylamine has been identified as such a powerful carcinogen that in order to provide an environmentally acceptable operation, an exceedingly expensive plant installation is indicated. The market for UDMH, on the other hand, is not large enough to justify such an expenditure.
The other method available for producing UDMH commercially is in accordance with the Raschig process which is based on the reaction of monochloramine with dimethylamine. This method, while presenting tedious problems associated with the recovery of the UDMH, is principally objectionable on another score in that the preparation of monochloramine can lead to the formation of trace quantities of trichloramine. The latter compound is so highly explosive that extreme care must be observed in order to assure that none of this unstable compound is produced.
It has recently been proposed to prepare UDMH by another reaction mechanism fundamentally differing from those of the aforementioned methods. Such a method, which is exemplified in East German Patent No. 76,520, is based upon the Hofmann rearrangement of 1,1-dimethylurea. The method of said patent, while environmentally acceptable and devoid of any tendency to produce hazardous or unstable compounds, is nonetheless beset with intricate processing problems. Without going into details relative to the problems involved, suffice it to say that this prior art process is difficult to implement because of the troublesome acidification of the highly basic reaction product specified therein combined with the extremely low concentration of unsymmetrical dimethylurea used. The long reaction times specified in said patent would require batch scale process equipment and consequently excessive investment costs.
In accordance with the improvement represented by the instant invention, the disadvantages associated with the prior art for converting unsymmetrical dimethylurea to UDMH can be obviated to the extent of rendering the method commercially attractive.